I dont think this is true there is redraw and reflow, absolutely positioned elements trigger redraw, but should only trigger reflow on child elements, z-index

I dont think this is true there is redraw and reflow, absolutely positioned elements trigger redraw, but should only trigger reflow on child elements, z-index has no effect on positioning, it only cares during redraw stage (which is as far as I understand, relatively lightweight compared to reflow)